2639808581 has 2 divisors, whose sum is σ = 2639808582. Its totient is φ = 2639808580.

The previous prime is 2639808547. The next prime is 2639808583. The reversal of 2639808581 is 1858089362.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1952844481 + 686964100 = 44191^2 + 26210^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2639808581 is a prime.

It is a super-2 number, since 2×2639808581² = 13937178688642467122, which contains 22 as substring.

Together with 2639808583, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2639808583) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1319904290 + 1319904291.

It is an arithmetic number, because the mean of its divisors is an integer number (1319904291).

Almost surely, 2^2639808581 is an apocalyptic number.

It is an amenable number.

2639808581 is a deficient number, since it is larger than the sum of its proper divisors (1).

2639808581 is an equidigital number, since it uses as much as digits as its factorization.

2639808581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 829440, while the sum is 50.

The square root of 2639808581 is about 51379.0675372763. The cubic root of 2639808581 is about 1382.0512415003.

The spelling of 2639808581 in words is "two billion, six hundred thirty-nine million, eight hundred eight thousand, five hundred eighty-one".